Oh, no!!! I'm so sorry we couldn't do anything to help! Don't blame yourself. They were probably sick when you got them.
It sounds to me like they had a wonderful home and lots of love while you had them. RIP Spectrum.

I'm sorry about Spectrum, it sounds like he was sick when you got him, and you did everything you could. Don't let this hold you back from future betta's.. you're not doing anything wrong. Swim free, Spectrum.